Cryostat Design: Case Studies, Principles and Engineering

293 Pages·2016·14.585 MB·English

by  J.G. Weisend II (eds.)

International Cryogenics Monograph Series
Series Editors: Steven W. Van Sciver · Sangkwon Jeong
J.G. Weisend II Editor
Cryostat
Design
Case Studies, Principles and Engineering
International Cryogenics Monograph Series
Series editors
Steven W. Van Sciver, Florida State University, Tallahassee, FL, USA
Sangkwon Jeong, KAIST, Daejeon, Korea, Republic of (South Korea)
TheInternationalEryogenicsMonographSerieswasestablishedintheearly1960s
to present an opportunity for active researchers in various areas associated with
cryogenic engineering to cover their area of expertise by thoroughly covering its
past development and its present status. These high level reviews assist young
researchers to initiate research programs of their own in these key areas of
cryogenic engineering without an extensive search of literature.
More information about this series at http://www.springer.com/series/6086
J.G. Weisend II
Editor
Cryostat Design
Case Studies, Principles and Engineering
123
Editor
J.G.Weisend II
European Spallation Source(ESS), ERIC
LundUniversity
Lund
Sweden
ISSN 0538-7051 ISSN 2199-3084 (electronic)
International Cryogenics MonographSeries
ISBN978-3-319-31148-7 ISBN978-3-319-31150-0 (eBook)
DOI 10.1007/978-3-319-31150-0
LibraryofCongressControlNumber:2016940359
©SpringerInternationalPublishingSwitzerland2016
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For Shari, Rachel, Alex
and Nick—As Always
Preface
Cryostats are technical systems that maintain equipment or cryogenic liquids at
cryogenic temperatures. As such, they are one of the fundamental building blocks
of cryogenic systems. Examples of cryostats include the magnet cryostats that
comprise the majority of the Large Hadron Collider (LHC) at CERN, spaceborne
cryostats containing sensors operating below 1 K, MRI cryostats found in most
large hospitals, and large cryogenic liquid storage vessels. Cryostats that contain
superconductingradiofrequencycavitiesarefrequentlyreferredtoascryomodules,
whilecryostatswhoseprincipalfunctionistostorecryogenicfluidsarealsoreferred
to as dewars. Cryomodules and dewars are also covered in this work.
The proper design of cryostats requires the knowledge of many disciplines
including cryogenic properties of materials, heat transfer and thermal insulation,
instrumentation, safety, structures, and seals. One of the best ways to learn about
cryostatdesignistostudythedesignchoicesandresultingperformanceofprevious
designs.
This book provides such a review. It starts with an introductory chapter on the
principlesofcryostatdesignincludingpractical dataandequations.Thischapteris
followed by a series of case studies on existing cryostats. The studies describe the
cryostat and the design choices made along with the resulting performance of the
cryostat. The cryostat examples used in the studies are chosen to cover the wide
rangeofcryostatapplicationsandtheauthorsofeachcaseareleadingexpertsinthe
field, all of whom participated in the design of the cryostats being described.
Chapters 2 and 3 are case studies involving superconducting magnets for large
particle accelerators. Due to the large numbers of magnets required in these cases,
low heat leak, reliability,and costare keyrequirements. Chapter 4describes aone
ofakindspacebornedewarsystemwhoserequirementsareverydifferentthanthat
of accelerator cryostats. Chapters 5 and 6 describe cryomodules that contain
superconducting RF cavities in particle accelerators. As will be seen there are two
broad families of these cryomodules (segmented and continuous) with different
designdriversandapproaches.Takentogetherthesechaptersdescribeatotalofsix
different cryomodules and the evolution of cryomodule design from the 1980s to
vii
viii Preface
the 2010s can be seen. Chapter 7 presents special topics in cryostat design. These
topics are of particular importance for MRI magnet cryostats; which provide the
examples but are broadly valuablefor all cryostats. Acryostatdesign for very low
(50mK)temperaturesisdescribedinChap.8.Inadditiontothelowertemperatures,
this cryostat has unique material requirements due to the need to keep the
radioactive background of the associated experiment as low as possible. Transfer
linesconnectcryostatsandareatypeofcryostatthemselves.Transferlinefeatures,
an overview of major transfer line systems, and a detailed case study of a transfer
line are found in Chap. 9. The final chapter provides a summary by listing
guidelinesforasuccessfulcryostatdesign.Extensivereferencesthroughoutprovide
sources offurther information.
Lund, Sweden J.G. Weisend II
June 2016
Acknowledgments
Thisbookwouldnothavebeenpossiblewithoutthecontributionsfromthechapter
authors, all of whom are involved in ongoing projects with very demanding
schedules. I wish to express my thanks to my co-authors for their hard work. Tom
Spicer, Cindy Zitter, and the team at Springer have been very supportive and
helpfulinthedevelopmentandproductionofthisbook.Iamhonoredthatthisbook
isbeingpublishedaspartofthelong-runningInternationalCryogenicMonograph
Series. Professor Steven Van Sciver, in addition to being one of the series editors,
wasalsomythesis advisoratWisconsinandIwouldliketothankhimformaking
this book possible in many ways than one. My colleagues at the European
Spallation Source and Lund University have also been a great help.
Asalways,thehelpandsupportofmyfamilyhasbeenthekeytothecompletion
of this book. For Shari, Rachel, Alex, and Nick—my continuing gratitude.
Lund, Sweden J.G. Weisend II
June 2016
ix
Contents
1 Principles of Cryostat Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
J.G. Weisend II
1.1 Cryostat Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Cryogenic Properties of Materials . . . . . . . . . . . . . . . . . . . . . 4
1.2.1 Thermal Contraction . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.2 Thermal Conductivity . . . . . . . . . . . . . . . . . . . . . . . 6
1.2.3 Heat Capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.2.4 Material Strength. . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.3 Thermal Insulation and Heat Transfer. . . . . . . . . . . . . . . . . . . 11
1.3.1 Reducing Conduction Heat Transfer . . . . . . . . . . . . . 11
1.3.2 Reducing Convection Heat Transfer. . . . . . . . . . . . . . 11
1.3.3 Reducing Radiation Heat Transfer. . . . . . . . . . . . . . . 12
1.3.4 Other Insulation Approaches. . . . . . . . . . . . . . . . . . . 15
1.4 Structural Supports for Cryostats . . . . . . . . . . . . . . . . . . . . . . 17
1.4.1 Alignment Approaches. . . . . . . . . . . . . . . . . . . . . . . 18
1.4.2 Suspension of Components from a Room
Temperature Top Flange . . . . . . . . . . . . . . . . . . . . . 19
1.4.3 Space Frames. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.4.4 Support Posts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
1.4.5 Supports in Space Cryogenics. . . . . . . . . . . . . . . . . . 23
1.5 Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
1.5.1 Temperature Measurement . . . . . . . . . . . . . . . . . . . . 24
1.5.2 Pressure Measurement . . . . . . . . . . . . . . . . . . . . . . . 27
1.5.3 Flow Measurement . . . . . . . . . . . . . . . . . . . . . . . . . 27
1.5.4 Level Measurement. . . . . . . . . . . . . . . . . . . . . . . . . 28
1.5.5 Installation, Wiring, Heat Sinking
and Feedthroughs . . . . . . . . . . . . . . . . . . . . . . . . . . 28
1.5.6 Commercial Availability of
Instrumentation Systems. . . . . . . . . . . . . . . . . . . . . . 30
1.5.7 Best Practices for Cryostat Instrumentation. . . . . . . . . 31
xi